1. Field of the Invention
This invention relates to a processor containing reconfigurable circuits wherein a circuit structure thereof can be changed and information processing apparatus equipped therewith.
2. Related Art
In recent years, a style of processing data successively according to processor instructions written by software using a microprocessor has been a main stream in today's information processing apparatuses. The style of using the microprocessor has remarkable advantages in that the function can be changed by changing a software program, a plurality of functions can be achieved by the same hardware and the like. As an importance thereof has increased, the processor is demanded to carry out processing at further higher speeds.
FIG. 1 is a block diagram showing a structure of major parts of a conventional processor.
In this processor 100, an instruction is inputted through a data bus 101a and stored in an instruction cache 101. If a predetermined instruction is read from this instruction cache 101, it is sent to an instruction decoder 102 through a bus OP and decoded there, so that a control signal is generated in bus CS. Each circuit block and bus in the processor are controlled by this control signal.
Data processing is carried out by an arithmetic operation between a register file 103 for storing source data necessary for the operation and function units(FU) 104-106. Data of the register file 103 is supplied to the function units 104-106 through bus RFD and a result of the operation is written back to the register file 103 through the bus 108. Data of the register file 103 is loaded and stored in the data cache 107 and vice versa. A processing unit comprises the function units 104, 105, 106, data cache 107 and data bus 108.
Although an arithmetic operation is carried out in the function units(FU) 104-106, only function units which are most frequently used are materialized as hardware to avoid an increase of chip area. That is, the function units 104-106 are constructed with arithmetic logic unit (ALU), floating point unit (FPU) and the like.
Because a user utilizes its own application here, installing a function unit for accelerating a particular application is effective for accelerating a particular application for individual users.
However, to reduce production cost of the processor, it is necessary to maintain a certain amount of production. A processor installed with a function unit restricted to a particular application like the aforementioned one increase its production cost because the demand therefor is lower than that for a general purpose processor. From this point of view, it is difficult to install, in the processor, a function unit oriented for a particular application. As a result, in carrying out a particular application, a sufficiently high speed cannot be achieved.